Sugar, spice and seasoning. From freshly ground pepper to artfully blended spice mixes, it’s no secret that humans are obsessed with flavour. But what about our most basic flavouring: salt? Why does every recipe seem to call for “a pinch of salt” or instruct you to “salt to taste?” This seemingly simple seasoning actually has a widespread impact on our food, bodies, health and culture. Generally, the salt humans eat is made of one molecule of sodium and one molecule of chlorine. Together, this ionic compound is called sodium chloride, or NaCl. Keep on reading to learn more about the functions of salt, its role in our body and some societal concerns regarding salt!
The Many Roles of Salt in Cooking
Salt does so much more than just provide a salty flavour to dishes. The Salt Association divides salt into 6 main jobs: seasoning, texture aid, binding agent, preservative, fermentation control and colour control (1).
We’re likely all familiar with the taste of salt, but adding salt to dishes can change the way we perceive other flavours and textures as well (1). In rice and potato chips, salt was found to enhance sweetness, mask metallic tastes, and balance the flavour profile overall. In soup, salt also makes it appear thicker and fuller (2). But why does this happen? It’s still a mystery that scientists are trying to solve!
Salt is also known for tenderizing and binding meats (1). This is due to the physical properties of salt. When NaCl is dissolved in water, the molecules separate and form ions- a process known as dissociation. The negatively charged chlorine ion is especially good at binding to proteins in meat, allowing them to become more liquid-like, causing them to swell, overall holding in more water (3). This ultimately results in a juicer, more tender meat!
Salt has also been used widely in preservation and fermentation (1). The Inuit were known for soaking fish in a salt solution- think of foods like beef jerky or kimchi (4-5). Salt brine can dehydrate bacterial cells and alter osmotic pressure, meaning that it can draw water out and prevent bacteria from growing, making food stay fresh and safe for longer (5). In baking, salt can also slow the growth of bacteria and yeast, which allows breads to rise slowly and steadily.
Finally, salt can help control the colour of food (1). It can be combined with other ingredients and chemicals to give meat the characteristics red-brown colour, and it can make bread look more golden through reducing sugar destruction.
Why Do We Need Salt?
Though people commonly talk about the importance of vitamins and minerals, we rarely seem to talk about the function of salt. In fact, salt is often deemed as unhealthy, which will be further discussed later on. However, there is a physiological need for salt. Specifically, the sodium ion in salt helps to carry out functions such as maintaining homeostasis, sending electrical signals through nerves and regulating blood pressure (6).
In terms of maintaining homeostasis, sodium is the major cation in the fluid outside our cells. It helps maintain resting membrane potential, which is a baseline difference in charge from the outside and inside environment of a neuron. When sodium flows into the neuron, it can conduct an electrical signal to the brain or muscles (7).
Sodium also acts like a magnet for water. Wherever sodium goes, water will try to follow. This is important in maintaining blood pressure. When certain hormones are released, the kidneys will reabsorb more sodium, thereby causing water reabsorption as well. This results in a high blood volume, which then causes higher blood pressure (6).
What Gives Salt its Salty Flavour?
Though we eat salt all the time, we rarely stop and consider what it means for something to actually be salty. It turns out, the human ability to taste salt is likely a product of evolution. We have two types of receptors that allow us to recognize the salty flavour (2).
Epithelial sodium channels (ENaCs) in our taste buds send signals to the brain when stimulated by dissolved sodium or even lithium. Essentially, ENaCs allow sodium to enter the taste receptor cell, and this increase in sodium causes neurotransmitters to be sent to the brain (8). And there you have it, you just tasted salt!
So why do we have a second receptor? It turns out that non-sodium salts can also give a salty taste. Remember that “salt” is a common name for an ionic compound. Humans can also taste potassium chloride, calcium chloride and ammonium chloride, though these are much more rare in food and often have an “off-taste” (2).
Why Is Salt “Unhealthy”?
Salt is undoubtedly important, but it has definitely gained a bad reputation in the past few years. Though salt has passed the test of evolution and is most definitely used in the body each day, excess amounts of it can cause many problems (2). Sodium has been identified as one of the main culprits in high blood pressure (9). Because it causes the reabsorption of water, high levels of sodium can cause chronic hypertension. This is dangerous, as high blood pressure increases the chance of other cardiovascular diseases and adverse events, such as stroke. Furthermore, excess sodium can worsen chronic kidney disease, cause osteoporosis and even increase the risk of stomach cancer (10).
As a side note, it is worth it to do a quick overview on why humans tend to overeat salt. As a species, we demonstrate salt preference; this means that humans like the taste of salt even when the physiological need for sodium is satisfied (2). Surprisingly, newborns actually have no salt preference, meaning that they don’t seem to crave the taste of salt much. However, after four months, they experience a “shift”, likely due to the maturation of their salt receptor, causing infants to begin choosing salty foods (2). Our preference for salt lasts into adulthood and has no definite limit. The more salt you eat, the more accustomed you are to the taste. This has some cultural implications, as we have lots of salty snacks and “hidden salt” in our foods.
How Do We Reduce Salt Intake? What are Salt Alternatives?
The World Health Organization (WHO) has said reducing salt-intake is one of the most cost-effective tactics to improve population health outcomes (11). An estimated 2.5 million deaths per year can be reduced globally if salt consumption was reduced to the recommended levels of approximately a teaspoon a day. But reducing salt intake comes with its challenges. As mentioned earlier, salt plays many roles in the texture, taste and safety of our food.
A majority of adult sodium intake comes from processed foods, rather than cooking. As such, the burden of reducing salt intake should start with large businesses rather than consumers. Studies have shown that incremental reductions of 5-10% are unnoticeable to consumers (2, 11). The salt taste receptor is also highly malleable; this means that it can adapt to new situations. If we eat less salt over time, we become accustomed to the flavour of less salty foods. The WHO has also recommended that local governments and food industries label foods with high sodium and implement consumer awareness programs (11). On a smaller level, restaurants can also remove salt shakers and soy sauce from tables, as well as add less salt during food preparation.
Research has also shown that the size of the salt particles may affect how intense the salt flavour is. Since sodium needs to be dissolved for it to activate taste buds, changing the size of each salt particle can improve its ability to dissolve, and allow us to taste the same salty flavour with less physical amounts of salt (2).
However, the main challenge is not maintaining flavour. Salt plays major roles in preserving foods and keeping them safe. Researchers are currently working on ways to prevent bacterial growth on foods with reduced sodium. An interesting approach is to mix traditional sodium chloride with other salts, such as potassium chloride (KCl). Though KCl has a somewhat bitter taste, it is difficult to taste in low amounts. Studies have shown that under 30-40%, people generally will not taste the bitterness (12). This switch allows salt to maintain its antimicrobial properties, without majorly affecting flavour or health.
Conclusion
Salt is a lot more complicated than it seems! Even though it’s such a versatile seasoning, it has a dark side to it. Next time you grab a salt shaker, think of the interesting applications of salt, both in cooking and health.
Glossary
Ionic Compound: A chemical substance made of a metal and non-metal ion
Cation: A positively charged ion that is formed by the loss of an electron
Homeostasis: The process of maintaining balance in the body. Homeostasis is the baseline “setting” that humans try to maintain.
Neurotransmitters: Molecules that signal to or between neurons.
Resting membrane potential: The difference in charge between the outside of a cell membrane and inside the cell. Resting membrane potential is created by charged ions.
Hypertension: High blood pressure
References
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